Ticket #18263: tax-doin-wrong-3.patch

wp-includes/taxonomy.php

@@ -311 +311 @@
                                         );
         $args = wp_parse_args($args, $defaults);
 
+        if ( false === $args['_builtin'] && ! empty( $wp ) && in_array( $taxonomy, array_merge( $wp->public_query_vars, $wp->private_query_vars ) ) )
+                _doing_it_wrong( __FUNCTION__, __( 'You should not use a reserved term when registering a taxonomy.' ), '3.3' );
+        
         if ( false !== $args['query_var'] && !empty($wp) ) {
                 if ( true === $args['query_var'] )
                         $args['query_var'] = $taxonomy;